You should be able to race the X30 Shifter in the Open Shifter class at the LAKC program. They just held their last race at the CalSpeed Karting facility last weekend. Also check to see if So-Cal Karters, Willow Springs or Buttonwillow have Open Shifter classes at their facilities.
The key to maintenance is going over the kart after every weekend on track. Check the kart for cracks, make sure all the nuts and bolts are tight, brake components are working properly. Engine wise, I normally consult with my engine service provider to see what I am suppose to be doing between races.